Yesterday after my '90 740 had been run for an hour or so and then parked for about 2 hours I jumped in, started it up and found it to making a heck of an exhaust roar. Inspection reveals that the outlet pipe of the catalytic converter is cracked completely around the circumference where it is welded to the converter body. This is a fairly new (3 years?) OEM cat and given how long they normally last and the excellent most recent test results I'm reluctant to simply buy another (was installed by independent shop 2,000 miles away, I doubt I can make a warranty claim...).

Two questions:

--At first glance this looks like it would be fairly simple to weld back together. Any reason why not?

-- Secondly, has anybody seen this before, and could it be something to do with too much tension/torque/whatever on the exhaust system? All hangers are in place and always have been, engine mounts are good, no obvious reason why the exhaust system should be stressed but perhaps I'm missing something?

Thanks for any advice...